A metal (from Greek μέταλλον métallon, "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typically malleable (they can be hammered into thin sheets) or ductile (can be drawn into wires). A metal may be a chemical element such as iron; an alloy such as stainless steel; or a molecular compound such as polymeric sulfur nitride.
In physics, a metal is generally regarded as any substance capable of conducting electricity at a temperature of absolute zero. Many elements and compounds that are not normally classified as metals become metallic under high pressures. For example, the nonmetal iodine gradually becomes a metal at a pressure of between 40 and 170 thousand times atmospheric pressure. Equally, some materials regarded as metals can become nonmetals. Sodium, for example, becomes a nonmetal at pressure of just under two million times atmospheric pressure.
In chemistry, two elements that would otherwise qualify (in physics) as brittle metals—arsenic and antimony—are commonly instead recognised as metalloids due to their chemistry (predominantly non-metallic for arsenic, and balanced between metallicity and nonmetallicity for antimony). Around 95 of the 118 elements in the periodic table are metals (or are likely to be such). The number is inexact as the boundaries between metals, nonmetals, and metalloids fluctuate slightly due to a lack of universally accepted definitions of the categories involved.
In astrophysics the term "metal" is cast more widely to refer to all chemical elements in a star that are heavier than helium, and not just traditional metals. In this sense the first four "metals" collecting in stellar cores through nucleosynthesis are carbon, nitrogen, oxygen, and neon, all of which are strictly non-metals in chemistry. A star fuses lighter atoms, mostly hydrogen and helium, into heavier atoms over its lifetime. Used in that sense, the metallicity of an astronomical object is the proportion of its matter made up of the heavier chemical elements.Metals, as chemical elements, comprise 25% of the Earth's crust and are present in many aspects of modern life. The strength and resilience of some metals has led to their frequent use in, for example, high-rise building and bridge construction, as well as most vehicles, many home appliances, tools, pipes, and railroad tracks. Precious metals were historically used as coinage, but in the modern era, coinage metals have extended to at least 23 of the chemical elements.The history of refined metals is thought to begin with the use of copper about 11,000 years ago. Gold, silver, iron (as meteoric iron), lead, and brass were likewise in use before the first known appearance of bronze in the 5th millennium BCE. Subsequent developments include the production of early forms of steel; the discovery of sodium—the first light metal—in 1809; the rise of modern alloy steels; and, since the end of World War II, the development of more sophisticated alloys.
Homework Statement
http://img35.imageshack.us/img35/6177/uthw404.jpg
Homework Equations
The Attempt at a Solution
I tried finding the center of mass of the square as if there were no hole in it, and then I added the radius of the circle to the x-coordinate of that. It's wrong...
Homework Statement
https://www.physicsforums.com/attachment.php?attachmentid=21003&stc=1&d=1255013927
I need help for number 11(b), (d)
The Attempt at a Solution
(b)(i) Electrons move towards the right since like charges repel.
(ii) Unlike Charges attract. Thus, positive...
Hello!
I just registered on these forums and this is my first post here, so hopefully I did everything right.
I recently got into metalworking in my spare time, and I am trying to create a metal alloy that will remain liquid at room temperature (a fusible, eutectic alloy). From what I've...
Metal Detectors!
Guys I an Undergraduate student in Lancaster University (England) and I have a passion for metal detecting when I am not in UNI. Over the years I have spoke many of my lecturers and research staff about the depth of a metal detector and its soul destroying ability to pick up...
first of all, i not sure whether this question should be posted here. seem the soil is more related to chemistry. :confused: Is Fe the highest concentration in the experiment extraction of heavy metal from organic oxidation phase (OO phase)? If so, why? thanks for helping ya.:smile:
A few questions about electric field here:
1. Why do charges have to be on the outer surface of the conductor?
2. Why no charge on the inner surface of a hollow conductor?
3. If charges cannot be inside the conductor, how come the electric potential is constant throughout the conductor when...
Metal inside a microwave oven --> ice?
When I was younger, I placed water inside a tin pan and placed it inside a microwave. I tuned it on, sparks went everywhere and I quickly turned it off. I took the pan out and it was solid ice. How?
A while ago I read an article in New Scientist that...
I recently purchased a new microwave oven, and there's a metal rack in it. The salesmen informed me that it shouldn't cause any problems as long as it didn't touch the sides; however, he was unable to tell me why this is. I have a basic understanding of how microwaves(as in the radiation not the...
What is the size of iron pentacarbonyl, methylcyclopentadienyl-manganese-tricarbonyl, or dicobalt octacarbonyl? Where could I find a source on this information?
I am aiming to fit the above carbonyls into a 29-34 angstrom pore, but I'd like to know if it's even possible given the size of the...
Homework Statement
A small metal sphere, carrying a net charge of q_1 = -2.60 \mu C, is held in a stationary position by insulating supports. A second small metal sphere, with a net charge of q_2 = -7.70 \mu C and mass 1.40 g, is projected toward q_{1}. When the two spheres are 0.800 \rm m...
Homework Statement
A Mg-Al alloy has a mass of 0.263 g and a density of 2.40 g/cm3. The density of pure Mg =
1.74 g/cm3 and for pure Al = 2.70 g/cm3. Calculate the % Mg in the alloy.Homework Equations
D=M/VThe Attempt at a Solution
Well I'm not really sure where to do. I solved for the volume...
Here's an interesting technology I came across:
http://en.wikipedia.org/wiki/Alkali-metal_thermal_to_electric_converter
So, from this I take it that a means of high-power conversion of nuclear thermal energy to electricity could be achieved. It says it only works upto 1400C, but that seems...
Homework Statement
Two metal balls A and B of negligible radius are floating at rest on Space Station Freedom between two metal bulkheads, connected by a taut nonconducting thread of length 1.30 m. Ball A carries charge q, and ball B carries charge 2q. Each ball is 1.66 m away from a bulkhead...
Homework Statement
Monochromatic light with a wavelength 415 nm strikes a metal surface. Photoelectrons escape with a kinetic energy of 95 kJ/mol. What is the work function (in kJ/mol, no decimals required) of the metal surface?
Homework Equations
I have found various equations online...
Homework Statement
The speed of sound in a metal rod is 3600 m s -1. The rod is 1.20m
long and clamped at one of its ends.
(a) Determine the frequency of its vibration if longitudinal waves
are established in the rod and it is vibrating in its first overtone
mode.
(d) Determine the...
There is a metal ball and a metal ring , through which the metal ball can pass easily. But when the metal ball is heated , it can't pass through the metal ring. What will happen if metal ring is heated?(keeping metal ball normal)
I am building a simple capacitor for experimentation and i have a question, or two.
At the moment i am using 30cm x 30cm (1 sqft) aluminum plates with a minuscule gap in between them as a capacitor. At the moment, even at the 200micro amp setting on my ammeter I get a very low reading (about...
1. Calculate the density of Na metal. The length of the body-centered cubic unit cell is 4.24 Å.2. Attempted solution:
[4 Na Atoms/unit cell] * [1 mol Na atoms/(6.022*10^23 atoms)] * [22.99g Na/1 mol Na] = 1.527 * 10-22 g/unit cell
(4.24 Å)3 = 7.6225 * 10-23 cm3/unit cell[1.527 * 10-22 g/unit...
Hi, Could someone give me some basic idea or information
1. How to measure the capacitance of interdigitated metal electrode of about 250 nm wide and 2 mm long on a silicon wafer, spacing between the electrode is 250 nm which is bonded bonded to copper pads.
2. Is it possible to measure the...
i found the average specific heat of a metal through an experiment it is 200. my only problem now is identifying it. i have tried many website but can't find anything useful please make some suggestions
Metal "permeability"
I went to the Von Braun planetarium the other day and was surprised to find out that their planetarium dome was a prototype for the Saturn V's Fuel tank! As a result, it wasn't exactly hemi-spherical which threw off come constellations, but that's another story.
I...
Comment: "When a metal is heated, there is current (ie flow of e) flowing too"
"We all know that metals are good conductors of heat. When one end of the metal is heated, the electrons will rapidly transfer the energy to the other end. This energy transfer often involves the flow of electrons...
Hello everyone,
I have a problem and need your help or advice.
Kindly check the drawing and help me.
Need to know how much force is generated at the free end when the gap closes to 200mm.
The length of the plate is 650 where 50 is welded and 600 is the free end
Material is...
Homework Statement
A metal (doesn't say what metal) is in a heater that is set to 700 K.
If the temperature of the ball is 900 K then the rate of heat loss = 0.10 J/min.
What is the rate of heat loss when the ball's temperature = 800 K.
The ball's emissivity doesn't change appreciably with...
You know how metal shavings form bows of flux lines. How is this possible since there are no discrete flux lines. I would think it should form a 2D gradient of shavings slowly graying out as they get further and further away. But you tend to see discrete lines as if at .4 inches there's a line...
Question
We have a bent piece of metal subjected to a shear V; we're to sketch the distribution of shear flow along the leg AB. (see attached)
What I've Done So Far
I've tried to determine the second moment of inertia but have failed to produce the same results given in the hints...
I am taking Engineering 101, and trying to get the hang of metal structure on a 'grains' level.
Ok, so my understanding is this;
Metals are polycrystalline materials, that can be divided up into 'grains'. These grains are basically crystals/lattices with a repeating pattern, separated by...
I am making a bonded magnet and have the need to maintain a temperature of around 70 C in a magnetic powder compressed in a stainless steel mold for a period of about 2 hours, before cooling rapidly to room temperature. i was thinking about using some sort of infra red heating, but would like to...
I'm struggling to understand how the stretched rubber & metal ball analogy explains the relativistic conception of gravity. It's possible that there is a simple and obvious solution to my confusion. It's also possible that this question has been answered many times. But I'll go ahead and ask...
Springs deform and basically change shape through atom rearrangement, but I wonder if the actual metal volume changes? Some of the atoms are pulled apart on the outer edges of the spring, while some of the atoms are rammed closer together on the inner portion. The total volume is conserved, or...
The temperature distribution on metal plate is given by...
Homework Statement
The temperature distribution on metal plate is given by
T(x,y) = 100/x^2+y^2+1
Calculate the direction derivative in the direction of v= <1,1> at the coordinates (3,2) and at coordinate (3,2) in what...
Hey mates,
I have a question that is probably really easy for you but i have no clue?
lets say we have a Magnetic field inside a coil. What I want to know is how big do I have to make that field so that the magnetic force will print an aceleration of let's say 1m/s^2 on a a metal bar.
I...
Homework Statement
Metal X
1) since the graph does not show that V is linearly related with I , is it right for me to apply the formula
R(50*C)=R(20*C) (1+ a lΔTl )
to find the temperature coefficient of metal X ?
2) R/Ω is linearly related with T/*C ?
If yes, will R=(dR/dT)T+c...
Homework Statement
A metal loop is attached to an axle with a handle as shown. The north pole of a magnet is placed blow the loop and handle turned so that the looks rotates counterclockwise at a constant angular speed.
Suppose the loop (the one above) were replaced by a second loop that...
I'm trying to formulate an completely liquid metal-based anti-freeze.
I was thinking on using Mn, but I'm not sure whether it will stay in an aqueous state
After I adding KMnO2 to water to get the Mn in aqueous state.
Any help?
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In Love
Prys die...
I read a question from a question paper..which went something like this...
There is a hollow metal sphere, initially uncharged, put in a uniform field. A field strength E0 is required to break the sphere. If the radius of the sphere is doubled, but the thickness of its walls is not changed...
help Calculus!
Homework Statement
got this question, and i need help. lost it lol. this is the sort of question i have to do for me assignment. Help in going through it
Homework Equations
Hot metal storage tank: is rectangle with a square cross section
total surface area is...
alright, so here's my question that i have to answer:
"A ball of mass .500kg is rolling across a table top with a speed of 5.00 m/s. When the ball reaches the edge of the table, it rolls down a frictionless incline onto the floor 1.00 meter below (without bouncing). What is the speed of the...
1. I need to know which compound out of Copper Sulfate, sodium chloride, potassium iodide and magnesium sulfate will be the best catalyst for the reaction between ALuminum metal and Hydrochloric acid.
2. The chemical equation is : 2Al(s) + 6HCl(aq) -> 2AlCl3(aq) + 3H2(g)
3. I...
Under an influence of a field, the electron distribution can be -
Theory A -
http://img147.imageshack.us/img147/1690/quantumelectrondistribu.png
or
Theory B -
http://img115.imageshack.us/img115/1690/quantumelectrondistribu.png
Theory B can be state wrong cause cause if...
Homework Statement
What exactly is the relative problem of extra accumilation of metals such as iron magnese and lead in fish? Do these metals cause problem with fish develoupment and fertility or do they effect the humans or animals that eat them?
Homework Equations
N/A
The...
Metal rod A is 0.300 m long expands by 6.50x10^-4 m when its temperature is increased by 100 degrees Celsius. Another rod made of different metal B and of the same length expands by 3.50x10^-4 m for the same increase in temperature. A third rod C, also 0.300 m long, is made up of pieces of the...
When a 35 gram piece of some metal at 100°C is placed in water, it loses 775 calories of heat while cooling to 30°C. Calculate the specific heat capacity of this metal.
Q = mc(DELTA)T
T = 70 degrees C
m = 35 g
Q = 775 cal ??
When i plugged it in i got 0.34 but the program said it...
Hey, I was looking at a car and the dealer told me the battery is at the back in the trunk. When he opened the hood he showed me how I would jump it if needed or anything else. He said there is one rod (that was visible coming through a connection from the battery) for the positive and for the...